Rules for Data Flow Diagram
Following are the rules which are needed to keep in mind while drawing a DFD(Data Flow Diagram).
- Data can not flow between two entities. –
Data flow must be from entity to a process or a process to an entity. There can be multiple data flows between one entity and a process.
- Data can not flow between two data stores
Data flow must be from data store to a process or a process to an data store. Data flow can occur from one data store to many process.
- Data can not flow directly from an entity to data store –
Data Flow from entity must be processed by a process before going to data store and vice versa.
- A process must have atleast one input data flow and one output data flow –
Every process must have input data flow to process the data and an output data flow for the processed data.
- A data store must have atleast one input data flow and one output data flow –
Every data store must have input data flow to store the data and an output data flow for the retrieved data.
- Two data flows can not cross each other.
- All the process in the system must be linked to minimum one data store or any other process.
Attention reader! Don’t stop learning now. Get hold of all the important CS Theory concepts for SDE interviews with the CS Theory Course at a student-friendly price and become industry ready.